The power dissipation of integrated circuit chips, such as processor chips, and the modules containing the chips, continues to increase in order to achieve increases in processor performance. This trend poses challenges at both the chip and system levels.
Power density is currently a major limiter of design performance. Power dissipation increases chip temperature, and fluctuations on a given processor chip can exceed 50° C., which can in turn cause discrepancies in transistor performance and result in reliability issues. High temperatures increase likelihood of timing or physical failures through electro-migration, as well as increasing device leakage current, which can lead to thermal runaway. These and other power-related effects drive the concept of ‘dark silicon’, which refers to the constraint that only so many transistors may be used simultaneously within a given thermal envelope. This limitation in the number of transistors available for simultaneous use imposes limits on a processor's capabilities and/or performance.
There are a number of cooling approaches to controlling temperature variations across a processor chip comprising one or more processor cores. These cooling approaches include providing a cooling airflow across the processor chip and/or heat sink coupled to the processor chip, as well as liquid-cooling solutions, wherein liquid passing through a liquid-cooled structure coupled to the processor chip absorbs heat dissipated by the chip. In other approaches, overall operation of the computer chip may be directly controlled in order to constrain heat dissipation from the chip. For instance, performance of the processor chip may be uniformly throttled in order to control heat dissipation from the chip. The disadvantage to this approach, however, is the reduced processing through-put resulting from throttling of the processor chip.